Cells- Topic 3- Movement of Substances Flashcards
3.1- forms of movement, 3.2- factors that affect movement
What is diffusion?
Is the: Movement of molecules with the concentration gradient, from high concentration to low concentration,
Common substances diffused: carbon dioxide, oxygen, water, urea.
As smaller molecules, Transported through pores.
What is facilitated diffusion?
Is the: Movement of substances with the concentration gradient from high concentration to low concentration.
Common substances diffused: glucose, amino acids, ions.
As bigger molecules, Transported through protein channel
What happens to a cell that is in a hypotonic solution? (compare the difference between plant and animal cells)
A hypotonic solution will burst an animal cell, but will swell a plant cell due to the cell wall.
What happens to a cell that is in a hypertonic solution? (compare the difference between plant and animal cells)
A hypertonic solution will shrivel an animal cell and will pull the cell membrane back from the cell wall in a plant cell.
What is osmosis?
Is the: movement of water from low solute concentration to high solute concentration.
What is active transport?
Is the: Movement of substances against the concentration gradient from low concentration to high concentration.
Common substances diffused: Glucose, ions.
Needs energy in the form of ATP needed. Transported through protein pumps.
What is endocytosis?
Is the: intake of soldi particles (like food).
1. Molecules move towards cell membrane and recognised by receptor.
2. Membrane invaginates and engulfs the molecule.
3. Cell membrane pinches off.
4. Vesicle formed with molecules inside.
What is exocytosis?
Is the: secretion of substances.
Uses ATP.
1. Substances packaged by Golgi body or (ROUGH) endoplasmic reticulum into a vesicle.
2. Vesicle transported to and fuses with the cell membrane.
3. Substances excreted.
Explain how the structure of a membrane facilitates different processes of movement through it.
Cell membrane has fluid mosaic model structure. As such, it is semi-permeable, facilitating the movement some substances more easily than others. Also facilitates it to be selective, meaning it can control the entry and exit of molecules.
Explain the roles of transport proteins, including channel proteins (such as aquaporins), and carrier proteins.
Cell membrane contains two types of embedded proteins: channel and carrier.
Protein channels: Passively transport charged or large molecules, like Aquaporins.
Aquaporins: transport water as it is charged. Aquaporins increase the membranes permeability to water and is in higher concentration in kidneys.
Carrier proteins: move ions and small molecules. Involved in passive or active transport. They have a binding site with specific shape to its solute.
How is the exchange of materials across membranes affected by the surface area to volume ratio of the cell?
As cell size increases:
- Surface area increases → increased exchange of materials.
- Volume increases → increased nutrients cell needs.
- Surface area to volume ratio decreases → decreased efficiency of the exchange of materials.
How is the exchange of materials across membranes affected by the concentration gradients?
The greater the concentration gradient, the faster the rate of diffusion.
How is the exchange of materials across membranes affected by the physical and chemical nature of the materials being exchanged?
Physical: Increased temperature means increased rate of diffusion.
Physical: Gasses diffuse more easily than liquids.
Chemical: Smaller and uncharged molecules diffuse quicker.
